Process for dehazing petroleum hydrocarbons with solid sodium silicate



United States Patent PROCESS FOR DEHAZING PETROLEUM HYDRO- CARBONS WITH SOLID SGDIUM SILICATE Glen D. Hunn, Pasadena, Tern, assignor to Sinclair Refining Company, New York, N.Y., a corporation of Maine This invention pertains to a method for removing undissolved Water from light liquid petroleum hydrocarbons. More particularly, this invention is concerned with the removal of such Water through contact of the hydrocarbon with a solid agent consisting essentially of sodium silicate disposed upon a solid carrier material.

The disadvantages of having dispersed but undissolved water in light petroleum hydrocarbons are very well known in the art. For instance, this water can cause undue corrosion of steel surfaces coming into contact with the wet hydrocarbon. If the corrosive tendencies of the hydrocarbon are inhibited by the addition of special chemical agents, undissolved water can lead to the necessity for incorporating larger amounts of the inhibiting agents than would be necessary if the undissolved Water were not present. Also undissolved water in the hydrocarbon can cause a haze throughout the liquid medium. Frequently such water is removed by contact with sodium chloride; however, it has been found that the salt can be carried from the treating vessel by the hydrocarbon stream and upon subsequent storage the salt forms a settled layer in the storage tanks which must be removed by washing.

These and other disadvantages resulting from the presence of dispersed but undissolved Water in light liquid petroleum hydrocarbons can be overcome in large part by contacting the wet hydrocarbon with a sodium silicate disposed on a solid adsorptive carrier material. The hydrocarbons treated in accordance with this invention are the normally liquid petroleum hydrocarbon materials boiling primarily below the gas oil range, for instance boiling principally below about 650 F. These are the light petroleum distillates which include, for example, gasoline, kerosene, household heating oils, jet fuels, etc.; and the stocks treated can be straight run or cracked materials.

I am aware that US. Patent No. 2,467,215 suggests the use of water-insoluble silicates of magnesium, calcium aluminum and other metals as dehumidifying agents for hydrocarbon oils; however, the sodium silicates of the present invention are sharply contrasted in that they are water-soluble. I prefer to employ sodium metasilicate. The sodium silicate is disposed on a solid adsorptive carrier such as diatomaceous earth, blast furnace slag, carborundum, etc. which carrier materials are essentially waterand hydrocarbon oil-insoluble. A preferred carrier is blast furnace slag of about 1" to 20 mesh size. Although these carrier materials show some tendency to remove undissolved water from hydrocarbon stocks the presence of the sodium silicate substantially enhances this action. In general the carrier will contain from about 1.0 to 1.8 weight percent of sodium silicate, with about 1.3 to 1.6 percent being preferred.

The hydrocarbon stock treated in accordance with the present invention will usually contain about .02 to .05 volume percent of dispersed but undissolved water and after treatment the amount of this water will generally lie in the range of about .003 to .007 percent. A convenient way of contacting the hydrocarbon and solid treating material is by disposing the latter as a stationary bed in an enclosed vessel. The hydrocarbon is then passed through the contact material at the desired rate; conveniently at a rate of about 4 to 1, preferably about 3 to 1 WHSV (weight of hydrocarbon per weight of solid contact material per hour). The hydrocarbon can flow in any direction through the bed of solid material, for instance upflow, downflow, etc. As the hydrocarbon passes through the contacting vessel undissolved water is removed and collects at the bottom of the tower where it can be withdrawn. Conveniently the temperature for treating the hydrocarbon is from about to 105 F but need only be below the boiling point of water.

The contacting agent of this invention, for example, can be prepared by first making a hot saturated solution of sodium metasilicate (about 5 lbs. per gallon of water). This solution is charged to a mixer along with mesh screened and washed blast furnace slag in the proportion of 2 gallons of solution per 8.5 cubic feet of slag. After mixing the material is deposited on a concrete slab for 1 hour to dry in the open air. The resulting material is charged as a bed to a contacting tower.

Contacting material prepared essentially by this procedure has been effective for removing undissolved water and for dehazing light and heavy gasoline fractions produced by the fluid catalytic cracking of gas oil. Typically the light fluid gasoline has a boiling range of about 95 to 250 F. and contains about .04 volume percent of undissolved water. It is passed through contact tower at approximately 3-1 WHSV and F., and the resulting hydrocarbon product contains .005 percent of undissolved water. Upon storage no salt precipitates from the hydrocarbon in the storage tank. The effective life of the contact material is at least several months under these processing conditions.

I claim:

1. In a method for removing undissolved water from References Cited in the file of this patent UNITED STATES PATENTS Stagni July 26, 1938 Stagner May 26, 1942 

1. IN A METHOD FOR REMOVING UNDISSOLVED WATER FROM LIGHT LIQUID PETROLEUM HYDROCARBON, THE STEP COMPRISING CONTACTING AT A TEMPERATURE FROM ABOUT 80 TO 105* F. SAID HYDROCARBON WITH SODIUM DISPOSED ON A SOLID, WATER- AND HYDROCARBON OIL-INSOLUBLE ADSORPTIVE CARRIER TO REMOVE UNDISSOLVED WATER FROM THE YDROCARBON FEEDSTOCK. 